1. Field of the Invention
The present invention relates to substrate treatment methods. More specifically, the present invention relates to a substrate treatment method which includes a step of etching a patterned resist layer or the like on a substrate of a semiconductor device, a liquid-crystal panel device or the like such as an IC or LSI, a step of removing the resist layer by a remover solution containing hydrofluoric acid and a succeeding rinsing step using a specific rinsing solution for lithography.
2. Description of the Related Art
Hitherto, manufacture of a semiconductor device or a liquid-crystal panel device such as an IC or LSI includes the following process: A photoresist is uniformly applied on a conductive metallic film such as of aluminum, copper or aluminum alloy, and/or an insulating film such as a SiO.sub.2 film which have been formed on a substrate; a latent image is drawn on the photoresist by exposure or electron-beam irradiation; the pattern is then developed to form a resist pattern; said conductive metallic film and/or insulating film are selectively etched using the resist pattern as a mask, thereby forming a fine circuit; and the unnecessary resist layer is removed using a remover solution.
Typical examples of remover solutions for removal of such a resist include organic sulfonic acid-based remover solutions containing alkylbenzenesulfonic acid as a principal ingredient, organic amine-based remover solutions containing an organic amine such as monoethanol amine as a principal ingredient, and hydrofluoric acid-based remover solutions containing hydrofluoric acid as a principal ingredient. Organic sulfonic acid-based remover solutions are, however, inferior in view of working conditions and environmental issues since a highly toxic organic solvent such as a phenol compound or chlorobenzene is used in the removing treatment, and in addition, they are disadvantageously corrosive for the conductive metallic film or the like on the substrate. Meanwhile, organic amine-based remover solutions have lower toxicity as compared to organic sulfonic acid-based remover solutions, therefore they do not require troublesome treatment for disposal of the waste solution, they exhibit good removing performance for degenerate films resulting from dry etching, ashing, ion implantation and other treatments, and in addition, they have superior anticorrosive effects for electrically conducting metal layer such as Al, Cu, Al alloy and the like which is formed on the substrate. Organic amine-based remover solutions, however, also have some drawbacks. For example, they cannot exhibit sufficient removing performance for resist films which have degenerated to the extent of possessing inorganic properties. Further, since the temperature for such removing treatment is relatively high as 60 to 130.degree. C., combustible organic compounds in such a remover solution may volatilize and be ignited, and therefore, expensive facilities are necessary for disaster prevention. As a result, the manufacturing cost becomes high. On the other hand, although hydrofluoric acid-based remover solutions exhibit superior removing performance for the aforementioned films which have degenerated to the extent of possessing inorganic properties, they are inferior regarding safety of the human body, namely, they are not easily handled. In addition, since a composition containing such a remover solution becomes acidic, it readily corrodes peripheral units such as a chemical solution-supplying unit which connects a removal treatment bath to a container containing the remover solution, and therefore, further complex processes are required for exhaust disposal and waste solution disposal.
Aiming at solving the above-described problems, the inventors have already proposed a remover solution in which the principal ingredient is a salt derived from hydrofluoric acid and a metal-free base (hereinafter, referred to as hydrofluoric acid-based remover solution). This hydrofluoric acid-based remover solution can achieve a low-temperature short-time removing treatment, can prevent metallic thin-films on the substrate and peripheral units from corroding, and can easily be treated for exhaust disposal or waste solution disposal due to its low toxicity. Such a remover solution, however, corrodes metallic thin-films such as Ti, Al, Al--Si or Al--Si--Cu films in a case where a washing process using pure water after the removing treatment requires a time period of above approximately 10 min. The inventors considered that such corrosion may be attributed to generation of hydrofluoric acid from the hydrofluoric acid salt due to contact with water, and conducted research on rinsing treatments in which various organic solvents such as methanol, ethanol, isopropyl alcohol and acetone were used and examined instead of pure water. These organic solvents were, however, found to be unsuitable since the hydrofluoric acid salt undesirably recrystallizes on the substrate.
Accordingly, an object of the present invention is to provide a substrate treatment method using a specific lithographic rinsing solution which does not corrode metallic thin-films on the substrate.
Further, another object of the present invention is to provide a substrate treatment method in which disposal of a substrate-rinsing solution after use can be carried out with a reduced volume of labor.